The genus Thaumetopoea Hübner (Lepidoptera: Notodontidae: Thaumetopoeinae) includes a dozen species commonly known as processionary moths. Most species are distributed on the southern range of the Western Palaearctic region (i.e. the Mediterranean Basin), but a few are adapted to cold conditions of high mountains (e.g. in the Alps) and high latitude (i.e. up to the Baltic Sea Basin).
The larvae feed on trees and shrubs of resin-rich families such as Pinaceae (pine, cedar), Anacardiaceae (pistachio, sumac), and Cistaceae, with the exception of one species feeding on Fagaceae (oak). Unusual high increases of populations – denoted as mass gradations – are occasionally observed in some species, then becoming serious pests for forestry or ornamental trees. The larvae share a very peculiar defence system, consisting of urticating setae they may release when disturbed. These setae can cause severe allergic reactions, and become a nuisance to both humans and domestic animals.
We summarise here information on the life history of the most common species in the genus Thaumetopea and discuss it in regards to lepidopteran relatives sharing key ecological characteristics (such as foraging patterns and defence strategies). Recent findings regarding phenological and distributional responses to climate change will also be discussed.